Tuesday , May 11 2021

Simulation against observation EurekAlert! Science News



(Santa Barbara, Calif.) – As an indicator of the effects of climate change, Arctic sea ice is difficult to beat. Scientists have observed the polar edges running in the sea and regenerated in this most sensitive region of Earth over decades to have an idea of ​​the possible effects on various natural systems: global ocean circulation , surrounding habitats and ecosystems, food sources, sea levels and more.

Despite attempts to make model simulations closer reflect actual observations of ice and Arctic sea melting, however, a gap has opened: Earth reports show that the ice melts at a much faster rate than predicted by global climate models.

"Based on this phenomenon, people have different views," said UC Santa Barbara's climate scientist, Qinghua Ding, an assistant professor at the campus Earth Research Institute. The consensus of the climate science community, he says, pushes towards the idea that the inconsistency is due to defective modeling. "Something like the model has some prejudice, it has some low sensitivity to anthropogenic enforcing," he explained.

Ding and his group disagree. In a study of the name "Remote of internal driver fingerprinting of Arctic sea ice in exemplary observations and simulations," published in the magazine Geoscience Natur, the group says that the models are very fine. About 40 to 50 per cent of ice and sea losses over the last three decades, they are arguing, are attributable to significant internal drivers but so far not yet understood – among them the effects of which are # 39 ; n occurs partly as far away as tropics.

"In fact, we compare apples to oranges," Ding said about the inconsistency between real-time observation and icewater Aroma simulated by anthropogenic driving. The average number of models, he explained, is accounts solely about the effects of historical radical enforcement – calculations mainly based on greenhouse gas levels – but they do not rely on, for example, The short term variations on the surface of the sea temperature, moisture, atmospheric pressure and other factors locally and have linked to other phenomena elsewhere on Earth. Such frequent frequency frequencies often appear as the individual running of individual simulations as scientists look for general long-term trends.

"Anyone running a model will have a random noise," said Bradley Markle, a postdoctoral scholar at Ding's research group. "If you take 20 or 30 running a model, they will all have a random chance, but they'll cancel each other." The consequential value is the average of all the simulations running without the random variation. But the random variation may also affect what is being observed on the ice, as well as the enforcement signal.

Due to their nature, internal variations are also likely to result in periods where ice ice Arctic appears to slow down or even reverse, but in the larger picture, climate scientists still see melting Arctic seagull completely for part of & year.

"There are many reasons we are focusing on ice and Arctic sea, but one of the main things that people really care for is the time of the ice cream summer," said Ding, referring to At a time when the northern pole is no longer frozen, it's been even in summer.

"At present, the prediction is that we will see a non-summer summer about 20 years," said Ding. More than just a climate issue, it continued, the ice-cream summer is also a social issue, given the effects on fisheries and other food sources as well as natural resources and habitats that benefit from the ocean sea. One of the things that this inconsistency between emulation and observation suggests, said, that predictions of when this ice-cream summer will take place with some recognition of the effects of variations will have to be tempted interior.

"There's a great uncertainty associated with this timeframe," Ding said. "As we consider internal variations, together with CO2 enforcing them, we should be more careful about the time of summer ice cream. "

For Markle, this situation highlights the disconnection that often occurs in terms of long-term climate trends against short-term observations. During our human timescales of hours to day, we experience atmospheric temperature changes over several degrees, so the mean global temperature increase of one or two degrees does not seem to be quite significant.

"Similarly, a year-on-year temperature variation, such as those associated with these tropical internal variations, can be several degrees in an annual average temperature in a specific area, so close to the same size with the global warming sign in the centuries, "he said.

An example of this relatively short climate variation is the known El Niño Southern Oscillation (ENSO), and the frequent tipping between El Niño and La Niña's weather systems that accompanies drought and rain, shortage and plenty to different parts of the world. ENSO is expected to be more extreme weather conditions because the Earth's climate is trying to balance even the average global temperature rise of even a few degrees.

"Only for reference to it, 20,000 years ago, a leaflet covered most of Canada during the height of the last ice age – which is changing the average annual temperature of four or five degrees," said Markle, "but it's a huge difference. "

Ding's research group continues to investigate mysterious and complex internal drivers affecting Arctic sea ice, especially those that occur in the warm wet tropics.

"We are very interested in the beginning of the 2000s to the present day, where we see such a strong melting," said Ian Baxter, a graduate student, who also works with Ding. It is known, added, that the effects of changes in the Arctic are no longer confined to the region and, in fact, are spread to center centers – often in the form of cases cold weather. The group is interested in how effects in the tropics could spread beyond that region and affect the Arctic.

###


Source link